Background technique
[0002] fuel atomizing of spraying from fuel nozzle has reduced the amount of the pollutant the exhaust effectively.Publication number is that the Japanese patent application of 2003-206828 (JP-A-2003-206828) and Japanese patent application that publication number is 2004-316598 (JP-A-2004-316598) have been described the fuel that the cavitation that causes fuel in fuel nozzle and injection mix with cavitation bubble.
[0003] is in the described technology of patent application of 2003-206828 at publication number, forms the edge protuberance that is projected in the fuel stream at the edge of valve seat.Fuel stream is separated from valve seat by described edge protuberance.The result causes cavitation.The upstream that edge protuberance is right after spray-hole is provided with.Therefore, the cavitation bubble that is produced by edge protuberance flows into spray-hole together with fuel.
[0004] be in the described technology of patent application of 2004-316598 at publication number, a plurality of spray-hole inlet channeles that extend from valve seat form in nozzle body.The downstream of spray-hole inlet channel interconnects by communication passage.A plurality of jetburner outlet passages also are formed in the nozzle body, and the jetburner outlet passage extends to each jet exit that the outer surface at nozzle body forms from communication passage.When fuel by the spray-hole inlet channel when valve seat flows to jet exit, in the spray-hole inlet channel, cause cavitation.And, fuel that in communication passage, flows and the entrance part collision of the fuel that flows out from the spray-hole inlet channel at the spray-hole outlet passage, collision energy has promoted the interference of the fuel stream in the spray-hole outlet passage, and has therefore promoted cavitation bubble to be mixed in the fuel stream.
[0005] yet, be in the described technology of patent application of 2003-206828 at publication number, because near spray-hole, cause cavitation, so fuel may be injected before fuel and cavitation bubble fully mix mutually.At publication number is in the described technology of patent application of 2004-316598, because the spray-hole inlet channel directly extends from valve seat, so the Flow area in the space between valve seat and the needle-valve has greatly influenced the generation of the cavitation in the spray-hole inlet channel.More properly, when needle-valve just when valve seat is removed, the Flow area in the space between valve seat and the needle-valve is very little.Like this, the Flow area of the Flow area in the space between valve seat and the needle-valve and spray-hole inlet channel is only slightly different.Therefore, when fuel when valve seat flows into the spray-hole inlet channel, the pressure of fuel only reduces a little, the result may not cause cavitation fully in the spray-hole inlet channel.
[0006] therefore, need to improve above-mentioned traditional fuel nozzle with atomized fuel fully.
Summary of the invention
[0007] the invention provides a kind of fuel nozzle that sprays the fuel that has fully atomized.
[0008] the present invention's first scheme relates to a kind of fuel nozzle, and it comprises a plurality of jet exits, valve seat, needle-valve, first cavity, second cavity, first fuel channel and a plurality of second fuel channel.Valve seat forms in fuel flows to the passage of a plurality of jet exits by it.Needle-valve is placed on the valve seat or from valve seat and removes.First cavity is arranged on the downstream of valve seat on the flow direction of fuel.Second cavity is arranged on the downstream of first cavity on the flow direction of fuel.First fuel channel is connected to second cavity with first cavity.The Flow area of first fuel channel is littler than the Flow area of first cavity.In a plurality of second fuel channels each is connected in a plurality of jet exits corresponding one with second cavity.The Flow area of each in a plurality of second fuel channels is littler than the Flow area of second cavity.
[0009] in such scheme, in a plurality of second fuel channels each can tilt with respect to the direction vertical with the bearing of trend of first fuel channel, makes each downstream side in a plurality of second fuel channels than each the upstream side of more close first fuel channel of upstream side in a plurality of second channels.
[0010] in such scheme, first cavity can be arranged on the axle of needle-valve.Second cavity can be along the circumference setting of the axle that centers on needle-valve.First fuel channel can upwards extend from the outer surface of first cavity in the footpath of needle-valve.
[0011] in above-mentioned scheme, fuel nozzle also comprise the nozzle body that holds needle-valve in it and be formed with valve seat with and the spray nozzle board of a plurality of jet exits of interior formation.First cavity can be formed by first gap between needle-valve and the spray nozzle board.First fuel channel and second cavity can be formed by second gap between nozzle body and the spray nozzle board.A plurality of second fuel channels can form in spray nozzle board.
[0012] in above-mentioned scheme, second gap can be along the circumference setting of the axle that centers on needle-valve.Second gap can comprise narrow gap and broad gap, and broad gap is than narrow relief width and be arranged on the outside in narrow gap diametrically.First fuel channel can be formed by narrow gap, and second cavity can be formed by broad gap.
[0013] in such scheme, narrow gap can form continuously along the circumference of the axle that centers on needle-valve.
[0014] in such scheme, broad gap can form continuously along the circumference of the axle that centers on needle-valve.
[0015] in such scheme, broad gap can comprise a plurality of broad gaps that are provided with predetermined interval along the circumference of the axle that centers on needle-valve.In a plurality of broad gaps each can be by corresponding at least one that is connected in a plurality of jet exits in a plurality of second fuel channels.
[0016] in above-mentioned scheme, second gap can be by forming at the recess and the bump that form on the surface of the nozzle body of spray nozzle board.
[0017] in above-mentioned scheme, after fuel was by the space between needle-valve and the needle stand, fuel flow to first fuel channel from first cavity.Then, fuel flows to second cavity by first fuel channel.When fuel is flowed through first fuel channel, owing to the boiling under the pressure that reduces causes cavitation.The cavitation bubble that produces in first fuel channel flows into second cavity with fuel.In second cavity, fuel and cavitation bubble mix mutually.Then, the fuel that mixes with cavitation bubble second fuel channel of flowing through makes fuel spray from jet exit.Therefore, fully mix burner oil afterwards mutually at fuel and cavitation bubble.This has improved the fuel atomizing of being sprayed.And fuel flows into first fuel channel by first cavity, rather than directly flows into first fuel channel from the space between needle-valve and the valve seat.This guaranteed when needle-valve just when valve seat is removed, just in first fuel channel, cause cavitation.
[0018] especially, in a plurality of second fuel channels each can tilt with respect to the direction vertical with the bearing of trend of first fuel channel, makes each downstream side in a plurality of second fuel channels than each the upstream side of more close first fuel channel of upstream side in a plurality of second channels.In this case, after first cavity flowed into second cavity, fuel was not to flow into second fuel channel from second cavity smoothly at fuel.This has increased fuel and has been retained in time in second cavity, and has promoted mixing of cavitation bubble and fuel.And, because each in a plurality of second fuel channels tilts with respect to the direction vertical with the bearing of trend of first fuel channel, make each downstream side in a plurality of second fuel channels than each the upstream side of more close first fuel channel of upstream side in a plurality of second channels, so can reduce by first fuel channel by because the possibility that the sludge that the inflow of combustion gas by jet exit forms blocks.Correspondingly, the mixing that can reduce cavitation bubble and fuel is adhered to the possibility that the sludge of the second cavity inboard suppresses.
[0019] first fuel channel and second cavity can be formed by second gap between nozzle body and the spray nozzle board.In this case, can easily form an integral passage, fuel flows to jet exit by this passage from the space between needle-valve and the valve seat.Especially, second gap can be by forming at the recess and the bump that form on the surface of the nozzle body of spray nozzle board.In this case, the shape of spray nozzle board is simple, and easier formation fuel nozzle.
Embodiment
[0021] to Fig. 3 the first embodiment of the present invention is described below in conjunction with Fig. 1.
[0022] Fig. 1 is the cross-sectional view of expression according to the end of the fuel nozzle of first embodiment of the invention.The spray nozzle board 20 that fuel nozzle according to first embodiment comprises needle-valve 4, holds the nozzle body 10 of needle-valve 4 and be connected to nozzle body 10.
[0023] the fuel fuel channel 6 of flowing through forms in nozzle body 10.Below fuel channel 6 is called " nozzle passage 6 ".Needle-valve 4 is contained in the nozzle passage 6.Needle-valve 4 to-and-fro motion on the direction of axle CL.Valve seat 12 forms in the outlet port of nozzle passage 6, and needle-valve 4 is placed on the valve seat 12.When needle-valve 4 on the direction of axle CL when valve seat 12 is removed, the outlet of nozzle 6 is opened, fuel is supplied to the zone in nozzle passage 6 downstreams then.When needle-valve 4 is placed on the valve seat 12, be interrupted to the supply of fuel of nozzle passage 6 downstream areas.
[0024] planar surface (attaching surface) 14 forms in the end of nozzle body 10.Spray nozzle board 20 is attached to attaching surface 14.Attaching surface 14 inboard form of recess 16 in nozzle body 10.Recess 16 is cylindrical around the axle CL of needle-valve 4.The bottom of recess 16 is near valve seat 12.When needle-valve 4 was placed on the valve seat 12, the end of needle-valve 4 did not protrude in the recess 16 or protrudes into slightly in the recess 16.
[0025] a plurality of fuel orifices 24 form in spray nozzle board 20.A plurality of fuel orifices 24 are as a plurality of second fuel channels.Fuel sprays by a plurality of fuel orifices 24.Each fuel orifice 24 extends to the opposed surface of spray nozzle board 20 from the surface towards the spray nozzle board 20 of nozzle body 10.When spray nozzle board 20 was attached on the nozzle body 10, the inlet face of each fuel orifice 24 was to recess 16.Each fuel orifice 24 makes progress with predetermined angle tilt in the footpath of needle-valve 4 with respect to the axle CL of needle-valve 4.
[0026] Yuan Xing bump 22 is forming on the surface of the spray nozzle board 20 of nozzle body 10.Bump 22 forms in the inboard of the inlet of fuel orifice 24.The external diameter of bump 22 is littler than the diameter of recess 16.When spray nozzle board 20 was attached on the nozzle body 10, bump 22 was positioned on the circumference of the axle CL of needle-valve 4.In other words, bump 22 is positioned at the inboard of recess 16.The internal diameter of bump 22 is mutually basic with the internal diameter of valve seat 12.The height (degree of depth) of the aspect ratio recess 16 of bump 22 is slightly little.When spray nozzle board 20 is attached on the nozzle body 10, between the bottom surface of the end face of bump 22 and recess 16, form narrow gap.
[0027] Fig. 2 is the amplification cross-sectional view (being the elliptical region that is centered on by dotted line among Fig. 1) of the part of displayed map 1.As shown in Figure 2, cavity 32 forms between the end of needle-valve 4 and spray nozzle board 20.Cavity 32 is surrounded by the interior perimeter surface of bump 22.Cavity 36 forms between nozzle body 10 and spray nozzle board 20.Cavity 36 is surrounded by the outer surface of the outer surface of recess 16 and bump 22.Cavity 32 is positioned at the upstream of cavity 36 on the fuel flow direction.Following cavity 32 will be known as " first cavity ", and cavity 36 will be known as " second cavity ".Fuel channel 34 interconnects two cavitys 32 and 36.Therefore, fuel channel 34 is as first fuel channel.Fuel channel 34 is formed by the gap between the bottom surface of the end face of bump 22 and recess 16.That is, second cavity 36 is formed by the broad gap between nozzle body 10 and the spray nozzle board 20, and fuel channel 34 is formed by the narrow gap between nozzle body 10 and the spray nozzle board 20.
[0028] Fig. 3 is the cross-sectional view that the line III-III along Fig. 1 is intercepted.As shown in Figure 3, first cavity 32 is the axle cylindrical spaces on the CL that are positioned at needle-valve 4.Second cavity 36 is the circular spaces around the axle CL of needle-valve 4.Fuel channel 34 is rounded around axle CL.Fuel channel 34 extends to the interior perimeter surface of second cavity 36 diametrically from the outer surface of first cavity 32.
[0029] fuel orifice 24 leads to second cavity 36.As shown in Figure 2, fuel orifice 24 is connected to second cavity 36 each jet exit 26 of the outlet of the spray-hole 24 that acts as a fuel.As shown in Figure 3, the inlet of fuel orifice 24 be set in qually spaced in around needle-valve 4 the axle CL circumference on.
[0030] action and the effect of describing according to first embodiment's fuel nozzle below in conjunction with accompanying drawing 2.In Fig. 2, arrow indication is when needle-valve 4 fuel mobile when valve seat 12 leaves.
[0031] when needle-valve 4 on the direction of axle CL when valve seat 12 is removed, make to be communicated with between the nozzle passage 6 and first cavity 32.Therefore, fuel flows into first cavity 32 from nozzle passage 6.Then, fuel flows into fuel channel 34 from first cavity 32.The Flow area of fuel channel 34 is little more a lot of than the Flow area of first cavity 32.Therefore, when fuel flowed into fuel channel 34, the flowing velocity of fuel increased, and correspondingly the pressure of fuel reduces.This reduction of fuel pressure causes the cavitation in the fuel channel 34.
[0032] fuel flows into second cavity 36 with the cavitation bubble that produces from fuel channel 34 in fuel channel 34.Then, fuel flows to the fuel orifice 24 in second cavity, 36 downstreams from second cavity 36.The Flow area of second cavity 36 is more a lot of greatly than the Flow area of each fuel orifice 24.Therefore, fuel is retained in a period of time in second cavity 36.And, because each fuel orifice 24 tilts with respect to the direction vertical with the bearing of trend of fuel channel 34, make the downstream side of each fuel orifice 24 than the upstream side of the more close fuel channel 34 of the upstream side of each fuel orifice 24, so fuel is not to flow to fuel orifice 24 from fuel channel 34 smoothly.This guarantees that fuel is retained in a period of time in second cavity 36.In the time of in fuel is retained in second cavity 36, fuel and cavitation bubble mix mutually.Therefore, flow into fuel orifice 24 with the well-mixed fuel of cavitation bubble.
[0033] therefore, in fuel nozzle, fully mix burner oil afterwards mutually at fuel and cavitation bubble according to first embodiment.This has promoted injected fuel atomizing.And in the fuel nozzle according to first embodiment, fuel flows into fuel channel 34 through first cavity 32, rather than directly flows into fuel channel 34 from the space between needle-valve 4 and the valve seat 12.This guaranteed when needle-valve 4 just when valve seat 12 is removed, just cause the cavitation in the fuel channel 34.
[0034] and, in fuel nozzle according to first embodiment, because each fuel orifice 24 tilts with respect to the direction vertical with the bearing of trend of fuel channel 34, make the downstream side of each fuel orifice 24 than the upstream side of the more close fuel channel 34 of the upstream side of each fuel orifice 24, therefore can reduce fuel channel 34 by because the possibility that the sludge that the inflow of combustion gas by jet exit 26 forms blocks.Correspondingly, the mixing that can reduce cavitation bubble and fuel is adhered to the possibility that the sludge of second cavity, 36 inboards suppresses.
[0035] fuel nozzle according to first embodiment also has the advantage relevant with production process.As mentioned above, the fuel channel 34 and second cavity 36 are formed by the gap between nozzle body 10 and the spray nozzle board 20.Therefore, 26 whole passage can easily form from nozzle passage 6 to jet exit.Especially, fuel channel 34 need be formed to cause cavitation effectively by narrow gap.Structure for according to first embodiment's fuel nozzle can accurately form the narrow gap that causes that effectively cavitation is required.
[0036] below in conjunction with Fig. 4 the second embodiment of the present invention is described.
[0037] Fig. 4 is the cross-sectional view of demonstration according to the end of the fuel nozzle of second embodiment of the invention.Fig. 4 and Fig. 3 similarity be, also illustrates the cross-sectional view that the fuel nozzle according to first embodiment of the invention is intercepted along the line III-III among Fig. 1.In Fig. 4, and mark with identical reference character according to the element of first embodiment's fuel nozzle and part components identical and part.Therefore will omit its unnecessary description.
[0038] according to second embodiment's fuel nozzle in the configuration aspects of second cavity 36 with different according to first embodiment's fuel nozzle.In a second embodiment, provide the second independent cavity 36 for each fuel orifice 24.Second cavity 36 is with the circumference setting of predetermined interval along the axle CL that centers on needle-valve 4.Second cavity 36 is to form by the recess 16 that forms nozzle body 10 with as shown in Figure 4 gear shape, rather than by with as first embodiment's cylindrical formation recess 16 form.The basic circle portion of gear shape recess 16 (base circle portion) is fixed on the outer surface of bump 22.Therefore, provide the second independent cavity 36 for each fuel orifice 24.
[0039] for above-mentioned structure, after first cavity 32 flowed into fuel channel 34, fuel was assigned to each of second cavity 36 from fuel channel 34 at fuel.Then, fuel is supplied to relevant fuel orifice 24.Therefore, can reduce the dead volume (dead volume) of the fuel in second cavity 36, remain on the effect that promotes the mixing of cavitation bubble and fuel in second cavity 36 simultaneously.In above-mentioned structure, fuel channel 34 is the same with first embodiment to be circular.Yet, when providing second cavity 36 separately, can provide fuel channel 34 separately for each fuel orifice 24 for each fuel orifice 24.
[0040] will the third embodiment of the present invention be described in conjunction with Fig. 5.
[0041] Fig. 5 is the cross-sectional view of end that shows the fuel nozzle of a third embodiment in accordance with the invention.Fig. 5 and Fig. 2 similarity be, illustrate demonstration according to first embodiment's fuel nozzle in Fig. 1 by the cross-sectional view of the amplification of the elliptical region that dotted line centered on.In Fig. 5, with according to the element of first embodiment's fuel nozzle and part components identical and part with identical reference character sign.Therefore will omit its unnecessary description.
[0042] in the 3rd embodiment, be flat towards the surface of the spray nozzle board 20 of nozzle body 10.Bump 18 forms in the recess 16 of nozzle body 10.Circular bump 18 is positioned on the circumference of the axle of needle-valve 4.The external diameter of bump 18 is littler than the diameter of recess 16.The diameter of the internal diameter of bump 18 and valve seat 12 is basic identical.The degree of depth of the aspect ratio recess 16 of bump 18 is slightly little.When spray nozzle board 20 is attached on the nozzle body 10, between the end face of bump 18 and spray nozzle board 20, form narrow gap.
[0043] in the 3rd embodiment, first cavity 32 forms between the end of needle-valve 4 and spray nozzle board 20.The space that first cavity 32 is surrounded by the interior perimeter surface of bump 18.Second cavity 36 forms between nozzle body 10 and spray nozzle board 20.The space that second cavity 36 is surrounded by the outer surface of the perimeter surface of recess 16 and bump 18.Fuel channel 34 is formed by the end face of bump 18 and the gap between the spray nozzle board 20.Fuel channel 34 interconnects two cavitys 32 and 36.
[0044] for above-mentioned structure, spray nozzle board 20 is flat plates.This has eliminated necessity of carrying out complicated forming process.And, the height of fuel channel 34, promptly the spacing between the end face of attaching surface 14 and bump 18 can be adjusted from the amount of the material of the end removal of bump 18 by adjustment.Therefore, can accurately form the narrow space that causes that effectively cavitation is required.
[0045] will the fourth embodiment of the present invention be described in conjunction with Fig. 6.Fig. 6 is the cross-sectional view of demonstration according to the end of the fuel nozzle of fourth embodiment of the invention.Fig. 6 and Fig. 2 similarity be, also described the cross-sectional view of the amplification of the elliptical region that shows that the fuel nozzle according to first embodiment is centered on by dotted line in Fig. 1.In Fig. 6, with according to the element of first embodiment's fuel nozzle and part similar elements and part with identical reference character sign.Therefore, its unnecessary description will be omitted.
[0046] in the 4th embodiment, be flat towards the surface of the nozzle body 10 of spray nozzle board 20.Circular recess 38, recess 40 and bump 22 form in spray nozzle board 20.Bump 22 is arranged between circular recess 38 and the recess 40.The degree of depth of the aspect ratio circular recess 38 of bump 22 is slightly little.When spray nozzle board 20 is attached on the nozzle body 10, between the end face of bump 22 and nozzle body 10, form narrow gap.
[0047] in the 4th embodiment, first cavity 32 forms between the end of needle-valve 4 and recess 40.Circular recess 38 is as second cavity 36.Fuel channel 34 is formed by the end face of bump 22 and the gap between the nozzle body 10.Fuel channel 34 interconnects two cavitys 32 and 36.
[0048], be flat towards the surface of the nozzle body 10 of spray nozzle board 20 for above-mentioned structure.This has eliminated necessity of carrying out complicated forming process.And, the height of fuel channel 34, promptly the spacing between the end face of attaching surface 42 and bump 22 is adjusted from the amount of the material of the end removal of bump 22 by adjustment.Therefore, can accurately form the narrow space that causes that effectively cavitation is required.
[0049] though described the present invention in conjunction with its exemplary embodiment, should be understood that the present invention is not limited to described embodiment or structure.On the contrary, can make multiple modification within the spirit and scope of the present invention.For example, can will combine with structure according to second embodiment's structure according to the 3rd embodiment.